1. Field of the Invention
The present invention relates to a network status server for distributing large-capacity data on a network, an information distribution system, a control method, and a storage medium for storing a control program.
Particularly, the present invention relates to a network status server, an information distribution system, a control method and a storage medium for storing a control program when a plurality of dispersed/arranged information distribution servers are controlled.
2. Related Background Art
As one of information distribution techniques using Internet, World Wide Web (hereinafter referred to as Web) has generally been used. This technique comprises: operating a web server software on a general computer (information processor); and distributing information such as contents (characters, charts, tables, and the like) described in an HTML language. The computer as a client which accesses a server (hereinafter referred to as the access client) may be connected to the server via a network, and free perusal is possible with a general-purpose perusal software (browser). In recent years, a web server site accessible to the entire world has appeared and the importance has further increased. On the other hand, when the web server has been accessed from the entire world in a concentrated manner, a large load is applied to the connection network, and the web server. To solve the problem, several techniques are currently proposed as countermeasures. The techniques will briefly be described with reference to FIGS. 6 and 7.
First, a system in which a virtual host computer is utilized as shown in FIG. 6 is proposed as a technique of dispersing accesses concentrated to the web server. This aims at dispersing the above-described load to a plurality of servers. In this example, it is supposed that the access client accesses URL (access address) of www.abcde.jp. In the access to www.abcde.jp, first the virtual host computer is accessed. The virtual host computer intends to appropriately disperse the accesses from the load situation of the respective subordinate web servers. Actually, any one of www1, www2, www3 distributes predetermined information in response to the access from the client, but the virtual host computer once accepts the access to appropriately disperse the access. Moreover, a transfer system by TCP connection hop is proposed. The system will be described with reference to FIG. 7. When there is an access from the client, first www1 is accessed. In the www1, a scheduler operates, and selects the optimum web server www3, and responds to the access from the client.
Specifically, the www1 constantly responds to an access request, and the optimum web server (www1, www2, www3) responds. In this system, the access dispersion is intended in the schedule function.
However, the above-described conventional access dispersion system has the following problems.
1) When the virtual host computer shown in FIG. 6 is utilized, a problem occurs that a device serving as an exclusive virtual host computer is separately necessary.
2) Moreover, when the exclusive virtual host computer temporarily accepts all the accesses, and when there are many accesses, the processing ability of the virtual host computer raises a problem. Specifically, the processing ability of the virtual host computer substantially indicates the processing ability of the web server site (the site in which the web server operates).
3) Moreover, in the virtual host computer system, the access is accepted in the server site in which the virtual host computer is present, the access of the web server in its own server site is leveled, and the respective virtual host computers are necessary for the respective web server sites provided with the dispersed/arranged web servers. Moreover, predetermined different URLs need to be set in the respective virtual host computers. Therefore, a problem occurs that the accessing client has to select the dispersed/arranged web server site by itself.
4) Furthermore, since the accessing client selects the web server site, a problem occurs that the accesses to the respective web server sites cannot be leveled.
However, the transfer system by the TCP connection hop as shown in FIG. 7 has an advantage that, different from the virtual host computer system, a mechanism for temporarily accepting the exclusive access is not separately necessary.
5) However, the accesses are concentrated on the web server in which the scheduler is permanently stationed. Therefore, if a trouble is generated in the web server in which the scheduler is permanently stationed, a problem occurs that the entire server site cannot function.
6) Moreover, in this system, the access to the dispersed/arranged web server site cannot be controlled to the optimum. Since the system is constituted for a purpose of leveling the access in the web server site (in its own network) managed by the scheduler, predetermined different URLs need to be set in the respective web server sites similarly as the above-described virtual site system. Therefore, there is a problem that the accessing client selects the dispersed/arranged web server site by itself.
7) Furthermore, similarly as the above-described virtual site system, since the accessing client selects the web server site, the accesses to the respective web server sites cannot be leveled.